Central Administration of Insulin Combined With Resistin Reduces Renal Sympathetic Nerve Activity in Rats Fed a High Fat Diet

Figures

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  FIGURE 1. Changes in renal sympathetic nerve activity (RSNA) expressed as percent, mean arterial pressure (MAP), and heart rate (HR) over time induced by the intracerebroventricular administration of insulin (n = 6) (500 mU/5 μl), resistin (n = 4) (7 μg/5 μl), control (saline, n = 5) (5 μl), and the combination of resistin and insulin (n = 7) in rats fed a normal chow diet. Upper panel for RSNA ∗P < 0.0001 insulin vs. saline; #P < 0.0001 insulin + resistin vs. insulin alone; and #P < 0.0001 insulin + resistin vs. resistin alone. Middle panel for MAP †P < 0.005 insulin vs. saline. Lower panel for HR ∗P < 0.0001 insulin + resistin vs. insulin alone and #P < 0.0001 insulin + resistin vs. saline.

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  FIGURE 2. Examples of original tracings of renal sympathetic nerve activity (RSNA) and integrated renal sympathetic nerve activity (IRSNA) before and after the administration of saline (5 μl), insulin (500 mU/5 μl), resistin (7 μg/5 μl), and the combination of resistin and insulin in rats fed a normal diet. Horizontal bar = 2 s; vertical bar = 200 mV for RSNA and 10 mV.s for IRSNA.

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  FIGURE 3. Changes in renal sympathetic nerve activity (RSNA) expressed as percent, mean arterial pressure (MAP), and heart rate (HR) over time induced by the intracerebroventricular administration of insulin (n = 5) (500 mU/5 μl), resistin (n = 5) (7 μg/5 μl), control (saline, n = 5) (5 μl) and the combination of resistin and insulin (n = 5) in rats fed a high fat diet. Upper panel, for RSNA ∗P < 0.0001 insulin vs. saline, ∗P < 0.0001 resistin + insulin vs. saline. #P < 0.0001 resistin + insulin vs. insulin alone, P < 0.0001 resistin + insulin vs. resistin alone. Middle panel, for MAP ∗P < 0.005 insulin vs. saline. Lower panel, for HR +P < 0.05 insulin vs. saline, +P < 0.05 resistin + insulin vs. saline. #P < 0.0001 resistin + insulin vs. insulin alone, #P < 0.0001 resistin + insulin vs. resistin alone.

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  FIGURE 4. Examples of original tracings of renal sympathetic nerve activity (RSNA) and integrated renal sympathetic nerve activity (IRSNA) before and after the administration of saline (5 μl), insulin (500 mU/5 μl), resistin (7 μg/5 μl), and the combination of resistin and insulin in rats fed a high fat diet. Horizontal bar = 2 s; vertical bar = 200 mV for RSNA and 10 mV.s for IRSNA.

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  FIGURE 5. Renal sympathetic nerve activity (RSNA) responses over time between rats fed a normal chow (ND) and a high fat diet (HFD), elicited by intracerebroventricularly administered resistin (n = 4 ND, n = 5 HFD) (7 μg/5 μl), insulin (n = 6 ND, n = 5 HFD) (500 mU/5 μl) and the combination of resistin and insulin (n = 7 ND, n = 5 HFD). ∗P < 0.01 between groups.

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  FIGURE 6. Mean arterial pressure (MAP) responses over time between rats fed a normal chow (ND) and a high fat diet (HFD), induced by intracerebroventricularly administered of resistin (n = 4 ND, n = 5 HFD) (7 μg/5 μl), insulin (n = 6 ND, n = 5 HFD) (500 mU/5 μl) and the combination of resistin and insulin (n = 7 ND, n = 5 HFD). ∗P < 0.001 between groups.

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  FIGURE 7. Heart rate (HR) responses over time between rats fed a normal chow (ND) and a high fat diet (HFD), induced by intracerebroventricularly administered of resistin (n = 4 ND, n = 5 HFD) (7 μg/5 μl), insulin (n = 6 ND, n = 5 HFD) (500 mU/5 μl) and the combination of resistin and insulin (n = 7 ND, n = 5 HFD). ∗P < 0.0001 between groups.

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  FIGURE 8. Effect of high fat diet (HFD; n = 18–19) on the body weight, food intake per day and average calorie intake per day over time compared to rats fed a normal chow diet (ND) (n = 18). #P < 0.005 and ∗P < 0.0001 between groups.